It is believed that sex intercourse, and other types of sexual activity, are among factors for improving close relationship between a human male and female couple. The performance of the sexual act requires the male a certain amount of strength and mobility of the lower part of the trunk. For a man without the necessary degree of strength and mobility, it would be difficult to perform the sexual act.
For those who are handicapped or otherwise physically weak, it would be desirable for them to utilize sex aid devices to compensate their physical deficiencies.